Publication Summary

The 1991 Marine Sediment Monitoring Task was conducted by the Washington State Department of Ecology as a component of the Puget Sound Ambient Monitoring Program (PSAMP). The marine sediment monitoring program is designed as a long-term monitoring effort to: 1) characterize baseline conditions, and 2) identify both natural and anthropogenic changes in Puget Sound. This report includes sediment chemistry, amphipod bioassay, and benthic infauna community data from 48 stations throughout Puget Sound.

The 1991 Marine Sediment Monitoring Task was conducted by the Washington State Department of Ecology as a component of the Puget Sound Ambient Monitoring Program (PSAMP). The marine sediment monitoring program is designed as a long-term monitoring effort to: 1) characterize baseline conditions, and 2) identify both natural and anthropogenic changes in Puget Sound. This report includes sediment chemistry, amphipod bioassay, and benthic infauna community data from 48 stations throughout Puget Sound.

The top two centimeters of sediment from at least five grab samples at each station were composited and homogenized. Samples were analyzed for toxicity using amphipod bioassays and for the presence of metals, semivolatile and volatile organic compounds (VOC), and chlorinated pesticides/PCBs. Five replicate grab samples were collected and analyzed for benthic infaunal community structure.

Sediments from Stations 34 (Sinclair Inlet), 35 (Dyes Inlet) and 21 (Port Gardner) exceeded state sediment quality standards for mercury. Concentrations of metals from all other stations were below state standards.

The highest concentration of VOCs were found at Stations 34 (Sinclair Inlet), 35 (Dyes Inlet), and Station 204R (East Sound, Orcas Island).

Concentrations of low and high molecular weight polycyclic aromatic hydrocarbons (PAH) were highest at Station 40 at the mouth of City Waterway. In contrast to results in 1989 and 1990, when normalized to total organic carbon, the concentration of LPAHs at Station 40 did not exceed state standards. Concentrations of beta-coprostanol were highest at Station 208R (Goose Point, Sequim Bay), followed closely by Station 41, adjacent to the Tacoma wastewater outfall. The polychlorinated biphenyl (PCB) Aroclor 1254 was detected in 25 samples, with the greatest concentration at Stations 35 (Dyes Inlet) and 33 (Elliot Bay). Aroclor 1260 was detected in six samples with the highest concentration at Station 34 in Sinclair Inlet. With the exception of 4,4'-DDT at nine stations an 4,4'-DDE and DDD at one station, no chlorinated pesticides were detected.

Comparison of test results to the negative control showed significantly increased amphipod mortality at only two North Sound and one Central Sound station.

Mean total abundance of benthic infauna ranged from 49.4 individuals per 0.2 m2 at Station 19 (Saratoga Passage) to 1693.8 at Station 41 (Blair/Sitcum Waterways), and the mean number of taxa ranged from 2.4 at Station 208R (Goose Point, Sequim Bay) to 123.8 at Station 26 (West Central basin).